When should I hold my son's first birthday?

My husband was out of town on our son's first birthday, it was kinda sad. So we had a party a week before his birthday, and then on his birthday I took him to the zoo. He probably doesn't remember any of it now, but it was fun watching him with all of the animals, and I took tons of pictures. All of the options you've suggested make sense. I would do something with him on his actual birthday, whether it's a small party with just you guys, or if you take him out to do something fun, and then another party either before or after that others can come to. You should find out from family members which week would be more convenient for them to come.

If i was in your situation i would probably do it on the sunday/saturday before. He might not have been born that day but a year before he was in your tummy about to come out ;]

Either is fine. We have done both. We usually have 2 parties, a family one and a friends one. You could do Monday and Saturday, so people have their choice of days. If they can't make one, ask if they want to come to the other. They can both have different "themes". I think 2 parties is very normal these days.